Aerosol corrosion inhibitors

ABSTRACT

Corrosion inhibitor compositions comprising a mixture of a nitroalkane containing 1-3 carbon atoms and a tertiary C 12-14  alkylammonium carboxylate selected from the group consisting of a C 12-14  alkylammonium benzoate and a tertiary C 12-14  alkylammonium-N-oleoyl sarcosinate. Such compositions are useful in inhibiting corrosion on the interior surfaces of tin-plated aerosol cans containing water-based aerosol formulations.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to corrosion inhibitor compositions which areuseful in inhibiting corrosion in aerosol products.

2. Description of the Prior Art

Many products designed for household, personal, automotive and othertypes of use are available as aerosol products. Typical examples of suchproducts include personal products such as hair care products (sprays,coloring agents and styling/conditioning mousses), deodorants,antiperspirants, first aid sprays, and colognes; household products suchas waxes, polishes, pan sprays, insecticides and room fresheners;automotive products such as cleaners and polishes; industrial productssuch as cleaners, lubricants and mold release agents; and animal careproducts such as tick and flea repellents.

Although some aerosol products are packaged in glass bottles or aluminumcans or lined steel cans, most formulations are loaded into unlined cansmade of tin-plated steel. While the tin affords protection againstcorrosion, the thinness of the coating, imperfections in the surface,wear and tear, and chemical action may ultimately expose the steel tothe contents of the can and corrosion can result. When aerosolformulations contain less than about 80 ppm (parts per million) water,corrosion of tin-plate cans is not generally a serious problem. However,if the water content of an aerosol formulation is more than 80 ppm,problems due to corrosion are more likely to occur.

The introduction of dimethyl ether (DME) as an aerosol propellant hasopened the way to the use of more water-based aerosol formulations andmade possible the manufacture of products of lesser flammability andlower ingredient cost. However, the use of water in such aerosolformulations also increases the problem of corrosion on the interior ofthe tin-plated steel cans which are so widely used, thus leading tocontamination of the aerosol product and ultimately to leaking of thecan if corrosion is severe enough. For this reason, corrosion inhibitorsare used with aerosol propellants containing DME, when this propellantis to be used in tin-plated steel cans containing a water-basedformulation.

The matter of inhibiting corrosion in an aerosol can presents the dualproblem of achieving corrosion inhibition in a system where there isboth liquid and vapor phase contact with the metal. In a system thatcontains DME and water, corrosion of the can in areas in contact withthe vapor phase is aggravated by the fact that relatively large amountsof water vapor are present along with the DME propellant in the vaporspace above the liquid contents of the container. For example, the vaporphase of a95/5 wt % dimethyl ether/water system contains 7,750 ppm watervapor at 70° F. (21.1° C.). Moreover, the addition of ethanol to aDME/water system will often exacerbate the problem of vapor phasecorrosion. A 90/5/5 (wt %) DME/ethanol/water system will contain 9,100ppm water vapor at 70° F.

SUMMARY OF THE INVENTION

Many commercially available corrosion inhibitors are either ineffectivefor aerosol systems containing DME or they fail to provide adequateprotection against both liquid phase and vapor phase corrosion. It oftenhappens that a corrosion inhibitor gives good protection where theliquid phase is in contact with the can but fails to provide protectionin areas where the interior surfaces of the can are in contact withvapor during storage. The reverse can also occur where the inhibitorgives good protection on the interior where there is contact with vapor,but poor protection where liquid normally contacts the container. Thepresent invention provides an improvement in aerosol compositionscontaining an aqueous aerosol-dispersible media and a propellant gas inwhich the improvement comprises the presence of a corrosion inhibitor inthe aerosol composition in a minor amount sufficient to providecorrosion inhibition to the composition. The corrosion inhibitor whichconstitutes the improvement in the aerosol composition is effectiveagainst both vapor phase and liquid phase corrosion, and it is comprisedof about 15 to 85 wt % of a nitroalkane containing 1-3 carbon atoms andabout to 85 to 15 wt % of a tertiary C₁₂₋₁₄ alkylammonium carboxylateselected from the group consisting of tertiary C₁₂₋₁₄ alkylammoniumbenzoate and tertiary C₁₂₋₁₄ alkylammonium-N-oleoyl sarcosinate. Suchcorrosion inhibitors are useful in a wide variety of aerosolcompositions where there is a need to protect the container fromcorrosive attack. As a general rule, this includes aerosol compositionsin which the formulation is water-based. Because of the compatibility ofDME with water, it is common in the aerosol industry to use DME as thepropellant gas either alone or in combination with other well knownaerosol propellants. Propellants such as, chlorodifluoromethane (FC-22),1-chloro-1,1-difluoroethane (FC-142b), 1,1-difluoroethane (FC-152a),hydrocarbons such as butane, isobutane and propane and compressed gasessuch as CO₂ and nitrogen and mixtures of these propellants can be usedin water-based aerosol formulations with or without DME. The corrosioninhibitor compositions of this invention can be used in aerosolscontaining any of these propellants or combinations thereof. Theintroduction of the inhibitor into the propellant prior to loading intothe aerosol can is a convenient way to incorporate the inhibitor intothe final aerosol formulation, and therefore, one of the objects of theinvention to provide aerosol propellant compositions containing one ormore propellants, such as those described above, in combination with thecorrosion inhibitor in an amount sufficient to provide corrosioninhibition in water-based aerosols.

The effectiveness of the two components of the corrosion inhibitorcompositions of the invention is not additive or supplementary but isgreater than expected or predicted from the performance of theindividual ingredients. Thus, neither the nitroalkanes nor thealkylammonium carboxylates performed entirely satisfactorily ascorrosion inhibitors in the liquid or the vapor phase of the aerosolformulations evaluated. Hence, it is clear that the effectiveness of thecorrosion inhibitor compositions of the invention is not simply theresult of blending liquid phase and vapor phase inhibitors.

DETAILED DESCRIPTION

The corrosion inhibitor compositions of this invention can be preparedby mixing commercially available materials. Nitroalkanes are, of course,well known compounds which are readily available commercially. Examplesof the nitroalkanes which are useful include nitroethane, 1-nitropropaneand nitromethane, the latter being the preferred compound. The tertiaryC₁₂₋₁₄ alkylammonium carboxylates can be prepared by mixing equimolaramounts of amine and carboxylic compound. The amines that are used aretertiary C₁₂₋₁₄ alkyl primary amines, such as "Primene 81-R" which is amixture of tertiary C₁₂₋₁₄ alkyl primary amines having highly branchedalkyl chains and molecular weights in the range of 185-213 and aneutralization equivalent of 191. The carboxylic compound which is mixedwith the amine can be benzoic acid (mol wt 122) or oleoyl sarcosine (molwt 353). The latter compound has the emperical formula, ##STR1## It isthe amide of oleic acid and sarcosine (CH₃ NHCOOH) also referred to asN-methyl glycine. Oleoyl sarcosine is available commercially and suchproducts usually come in admixture with small amounts (up to 6 wt %)free oleic acid which should be taken into consideration in determiningthe amount of sarcosine needed to be equimolar to the amine.

The proportion of the two constituents that form the inhibitorcomposition can be in the range of 15 to 85 wt % nitroalkane and 85 to15 wt % carboxylate. A preferred range is 15 to 50 wt % nitroalkane and85 to 50 wt % carboxylate. A 50/50 mixture by weight is a preferredcomposition. The optimum concentration of inhibitor composition neededto obtain effective corrosion inhibition will, of course, vary with theformulation in which it is to be used, and it can be determined bystorage tests, such as those described in the Examples. Generally, theeffective concentration range is 0.2 to 2 wt % based on the total weightof the aerosol formulation including the weight of a propellant as wellas the weight of the other ingredients. A preferred weight range is 0.5to 1 wt % of the aerosol formulation. The inhibitors can be addeddirectly to the aerosol can either alone or mixed with othernon-pressurized ingredients, or if preferred, they can be introduced assolutions in the propellant in an amount which when incorporated withthe other ingredients will provide the desired 0.2 to 2 wt % ofcorrosion inhibitor in the final composition.

The composition of the aqueous aerosol-dispersible media which is, inessence, the formulation containing the active ingredients, will, quitenaturally, depend upon the use for which the aerosol is designed. Suchformulations are well known to persons skilled in the art, and thechoice of formulation is not critical to the use of the invention solong as the medium is compatible with the components of the inhibitorcomposition. The use of the corrosion inhibitors in tin-plated cans withdry-type antiperspirants containing aluminum chlorohydrate is notrecommended. Lined cans should be used in these instances.

EXAMPLES

Sixty-day corrosion tests at 120° F. (48.9° C.) were run on thecorrosion inhibitors in three aerosol formulations. These formulationswere selected as being representative of commercial products, in theirchemical compositions. Distilled water was used in each of the fiveformulations because it was readily available in the laboratory.However, similar results would be expected with deionized water which isoften used in commercial aerosols.

    ______________________________________                                        Component             Wt. %                                                   ______________________________________                                        Formulation No. 1                                                             Insecticide (pH = 6)                                                          Natural pyrethrins    1.50                                                    Piperonyl butoxide    0.65                                                    Polyglyceryl fatty acid                                                                             0.97                                                    ester surfactant ("Witconol 14"                                               Witco Chemical Corp.)                                                         Ethanol (SDA 40-1)    10.01                                                   Water (distilled)     51.87                                                   Dimethyl ether        35.00                                                   Formulation No. 2                                                             Insecticide (pH = 5)                                                          Phosphorothioic acid O,                                                                             0.98                                                    O--diethyl O--(3,5,6-trichloro-                                               2-pyridyl) ester                                                              Natural pyrethrins    0.06                                                    Piperonyl butoxide    0.13                                                    Polyglyceryl fatty acid ester                                                                       0.20                                                    surfactant                                                                    Water (distilled)     63.63                                                   Dimethyl ether        35.00                                                   Formulation No. 3                                                             Hairspray (pH = 7.2)                                                          Vinyl acetate/crotonic acid/                                                                        2.50                                                    vinyl neodecanoate                                                            terpolymer                                                                    2-amino-2-methyl-1-propanol                                                                         0.20                                                    Modified lauric alkanolamide                                                                        0.10                                                    Silicone glycol copolymer                                                                           0.05                                                    Ethanol (SDA 40-1)    37.15                                                   Water (distilled)     10.00                                                   Chlorodifluoromethane (FC-22)                                                                       20.00                                                   Dimethyl ether        30.00                                                   ______________________________________                                    

Procedure

All of the examples were prepared using the following procedure. Theactive ingredients were weighed individually into an eight-ouncethree-piece aerosol can 21/8" in diameter and 5 9/16" long, except whenthe corrosion inhibitors were added to the aerosol can as a solution inthe propellant (noted in tables). The can was purged withdichlorodifluoromethane (FC-12) vapor to displace the air in thecontainer. The aerosol can valve was then placed into the can andcrimped. The propellants were introduced into the can as liquids throughthe aerosol valve. Volume amounts corresponding to the weights of thepropellants were calculated prior to loading, and a glass, calibrated,pressure buret was used to measure and transfer the liquids from storagecylinders to the can. A nitrogen gas pressure of 100 psig was applied tothe buret to aid in transferring the liquids from the buret to the can.After the propellant was loaded, the can was weighed, and the weight ofpropellant recorded.

The aerosol cans used in the corrosion tests were commercially availablecontainers and are described in trade literature as: one inch round dometop unlined aerosol containers, size 202×509 (21/8" diameter, 5 9/16"can wall height), 0.25 lb. electrolytic tin-plated (ETP), full concavebottom with welded side seam.

A corrosion test rating system was used which provides a complete visualdescription of the appearance of the interior surface of the tin-platedsteel aerosol cans after 60 days storage at 120° F.

    ______________________________________                                        CAN CORROSION - RATING SYSTEM                                                 Rating*           Description                                                 ______________________________________                                        0                 No Corrosion                                                1                 Trace Corrosion                                             2                 Light Corrosion                                             3                 Moderate Corrosion                                          4                 Heavy Corrosion                                             5                 Severe Corrosion                                            ______________________________________                                         *This numerical rating is an overall assessment of the total can              (tinplate, joints and side seams) and represents the primary rating of a      test. A rating of 0-2 is considered effective and 3 or greater is a faile     rating.                                                                  

The tertiary C₁₂₋₁₄ alkylammonium benzoate used was prepared by heatingto 55°-60° C. 0.5 mol (95.5 g) of a mixture of tertiary C₁₂₋₁₄ alkylamines from Rohm and Haas Company ("Primene 81-R" neutralizationequivalent 191) in a 500 ml beaker and then adding 0.5 mol (61 g) ofbenzoic acid while stirring. The final product was a very viscous amberliquid. The tertiary C₁₂₋₁₄ alkyl ammonium-N-oleoyl sarcosinate wasprepared by thoroughly mixing 100 g of commercially available oleoylsarcosine [Sarkosyl® 0 from Ciba-Geigy Corporation containing 6 g (0.02mol) oleic acid and 94 g (0.27 mol) oleoyl sarcosine] with 0.29 mol(55.4 g) of "Primene 81-R". The final product was a viscous amberliquid.

                                      TABLE NO. 1                                 __________________________________________________________________________    CORROSION TEST DATA                                                                         Corrosion                                                                           Corrosion                                                               Test  Test   Test                                                                              Description of                                 Corrosion Inhibitor                                                                     Wt. %                                                                             Procedure                                                                           Medium Rating                                                                            Test Can Corrosion                             __________________________________________________________________________    None      --  60 days at                                                                          Formulation                                                                          5   Bottom detinned;                                             120° F.                                                                      No. 1      rust on walls;                                                                vapor phase rusted                             Tertiary C.sub.12-14                                                                    0.50                                                                              60 days at                                                                          Formulation                                                                          1   Slight vapor                                   alkylammonium-                                                                              120° F.                                                                      No. 1      phase corrosion                                N--oleoyl                                                                     sarcosinate                                                                   Tertiary C.sub.12-14                                                                    0.50                                                                              60 days at                                                                          Formulation                                                                          2   Light corrosion                                alkylammonium 120° F.                                                                      No. 1      on side seams and                              benzoate                       bottom-joint;                                                                 slight vapor phase                                                            rusting                                        Nitromethane                                                                            0.50                                                                              60 days at                                                                          Formulation                                                                          3   Moderate corrosion                                           120° F.                                                                      No. 1      in liquid and                                                                 vapor; detinning                                                              in liquid                                      Tertiary C.sub.12-14                                                                    0.25                                                                              60 days at                                                                          Formulation                                                                          0   No corrosion                                   alkylammonium 120° F.                                                                      No. 1                                                     benzoate                                                                      Nitromethane                                                                            0.25                                                                Tertiary C.sub.12-14                                                                    0.25                                                                              60 days at                                                                          Formulation                                                                          0   No corrosion                                   alkylammonium-N--                                                                           120° F.                                                                      No. 1                                                     oleoyl                                                                        sarcosinate                                                                   Nitromethane                                                                            0.25                                                                __________________________________________________________________________

                                      TABLE NO. 2                                 __________________________________________________________________________    CORROSION TEST DATA                                                                         Corrosion                                                                           Corrosion                                                               Test  Test   Test                                                                              Description of                                 Corrosion Inhibitor                                                                     Wt. %                                                                             Procedure                                                                           Medium Rating                                                                            Test Can Corrosion                             __________________________________________________________________________    None      --  60 days at                                                                          Formulation                                                                          5   Severe corrosion                                             120° F.                                                                      No. 2      in liquid and                                                                 vapor phase                                    Tertiary C.sub.12-14                                                                    0.50                                                                              60 days at                                                                          Formulation                                                                          2   Light vapor                                    alkylammonium-                                                                              120° F.                                                                      No. 2      Phase corrosion                                N--oleoyl                                                                     sarcosinate                                                                   Tertiary C.sub.12-14                                                                    0.50                                                                              60 days at                                                                          Formulation                                                                          2   Light vapor                                    alkylammonium 120° F.                                                                      No. 2      phase corrosion                                benzoate                                                                      Nitromethane                                                                            0.50                                                                              60 days at                                                                          Formulation                                                                          5   Similar to control                                           120° F.                                                                      No. 2                                                     Tertiary C.sub.12-14                                                                    0.25                                                                              60 days at                                                                          Formulation                                                                          0   No corrosion                                   alkylammonium 120° F.                                                                      No. 2                                                     benzoate                                                                      Nitromethane                                                                            0.25                                                                Tertiary C.sub.12-14                                                                    0.25                                                                              60 days at                                                                          Formulation                                                                          0   No corrosion                                   alkylammonium-                                                                              120° F.                                                                      No. 2                                                     N--oleoyl                                                                     Sarcosinate                                                                   Nitromethane                                                                            0.25                                                                __________________________________________________________________________

                                      TABLE NO. 3                                 __________________________________________________________________________    CORROSION TEST DATA                                                                         Corrosion                                                                           Corrosion                                                               Test  Test   Test                                                                              Description of                                 Corrosion Inhibitor                                                                     Wt. %                                                                             Procedure                                                                           Medium Rating                                                                            Test Can Corrosion                             __________________________________________________________________________    None      --  60 days at                                                                          Formulation                                                                          5   Severe liquid                                                120° F.                                                                      No. 3      phase detinning;                                                              spots of rusting                                                              and detinning in                                                              vapor zone                                     Tertiary C.sub.12-14                                                                    0.50                                                                              60 days at                                                                          Formulation                                                                          4   Severe liquid                                  alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning;                               N--oleoyl                      no rusting                                     sarcosinate                    evident                                        Nitromethane                                                                            0.50                                                                              60 days at                                                                          Formulation                                                                          5   Same as control,                                             120° F.                                                                      No. 3      except large rust                                                             areas in both                                                                 phases                                         Tertiary C.sub.12-14                                                                    0.10                                                                              60 days at                                                                          Formulation                                                                          4   Severe liquid phase                            alkylammonium-                                                                              120° F.                                                                      No. 3      detinning                                      N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.10                                                                Tertiary C.sub.12-14                                                                    .sup. 0.25.sup.a                                                                  60 days at                                                                          Formulation                                                                          4   Severe liquid phase                            alkylammonium-                                                                              120° F.                                                                      No. 3      detinning                                      N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.25                                                                Tertiary C.sub.12-14                                                                    .sup. 0.50.sup.a                                                                  60 days at                                                                          Formulation                                                                          2   Light liquid phase                             alkylammonium-                                                                              120° F.                                                                      No. 3      detinning                                      N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.50                                                                Tertiary C.sub.12-14                                                                    .sup. 1.00.sup.a                                                                  60 days at                                                                          Formulation                                                                          3   Moderate liquid                                alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning                                N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            1.00                                                                Tertiary C.sub.12-14                                                                    .sup. 0.10.sup.a                                                                  60 Days at                                                                          Formulation                                                                          3   Moderate liquid                                alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning                                N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.50                                                                Tertiary C.sub.12-14                                                                    0.25                                                                              60 Days at                                                                          Formulation                                                                          3   Moderate liquid                                alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning                                N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.50                                                                Tertiary C.sub.12-14                                                                    0.50                                                                              60 Days at                                                                          Formulation                                                                          2   Light liquid                                   alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning                                N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.10                                                                Tertiary C.sub.12-14                                                                    0.50                                                                              60 Days at                                                                          Formulation                                                                          2   Light liquid                                   alkylammonium-                                                                              120° F.                                                                      No. 3      phase detinning                                N--oleoyl                                                                     sarcosinate                                                                   Nitromethane                                                                            0.25                                                                __________________________________________________________________________     .sup.a Corrosion inhibitors were dissolved in propellant and added to         aerosol cans as propellant solutions. All other samples were prepared by      adding corrosion inhibitors and propellant individually to aerosol cans. 

                                      TABLE NO. 4                                 __________________________________________________________________________    CORROSION TEST DATA                                                                         Corrosion                                                                           Corrosion                                                               Test  Test   Test                                                                              Description of                                 Corrosion Inhibitor                                                                     Wt. %                                                                             Procedure                                                                           Medium Rating                                                                            Test Can Corrosion                             __________________________________________________________________________    None      --  60 days at                                                                          Formulation                                                                          5   Severe detinning in                                          120° F.                                                                      No. 1      liquid and vapor                                                              zones; considerable                                                           corrosion in both                                                             phases                                         Nitroethane                                                                             0.50                                                                              60 days at                                                                          Formulation                                                                          3   Some detinning in                                            120° F.                                                                      No. 1      liquid phase. Rust                                                            spots in liquid and                                                           vapor zones                                    1-Nitropropane                                                                          0.50                                                                              60 days at                                                                          Formulation                                                                          3   Some detinning in                                            120° F.                                                                      No. 1      liquid phase. Rust                                                            spots in liquid and                                                           vapor zones                                    Tertiary C.sub.12-14                                                                    0.25                                                                              60 days at                                                                          Formulation                                                                          1   Trace detinning                                alkylammonium 120° F.                                                                      No. 1      in vapor zone                                  benzoate                                                                      Nitroethane                                                                             0.25                                                                Tertiary C.sub.12-14                                                                    0.25                                                                              60 Days at                                                                          Formulation                                                                          1   Trace detinning                                alkylammonium 120° F.                                                                      No. 1      in vapor zone                                  benzoate                                                                      1-Nitropropane                                                                          0.25                                                                __________________________________________________________________________

I claim:
 1. In an aerosol composition containing an aqueousaerosol-dispersible medium and a propellant, the improvement whichcomprises the presence of a corrosion inhibiting composition comprising15 to 85 wt. % of a nitroalkane containing 1-3 carbon atoms and 85 to 15wt. % of a tertiary C₁₂₋₁₄ alkylammonium carboxylate selected from thegroup consisting of a tertiary C₁₂₋₁₄ alkylammonium benzoate and atertiary C₁₂₋₁₄ alkylammonium-N-oleoyl sarcosinate, said corrosioninhibiting composition being present in an amount sufficient to preventmore than light corrosion of a tin-plated steel aerosol can containingsaid aerosol composition.
 2. The composition of claim 1 in which thenitroalkane is nitromethane and the tertiary C₁₂₋₁₄ alkylammoniumcarboxylate is a tertiary C₁₂₋₁₄ alkylammonium benzoate.
 3. Thecomposition of claim 1 in which the nitroalkane is nitromethane and thetertiary C₁₂₋₁₄ alkylammonium carboxylate is a tertiary C₁₂₋₁₄alkylammonium-N-oleoyl sarcosinate.
 4. The composition of claim 1comprising 15 to 50 wt. % of a nitroalkane containing 1-3 carbon atomsand 85 to 50 wt. % of a tertiary C₁₂₋₁₄ alkylammonium carboxylate. 5.The composition of claim 4 in which the nitroalkane is nitromethane andthe tertiary C₁₂₋₁₄ alkylammonium carboxylate is a tertiary C₁₂₋₁₄alkylammonium benzoate.
 6. The composition of claim 4 in which thenitroalkane is nitromethane and the tertiary C₁₂₋₁₄ alkylammoniumcarboxylate is a tertiary C₁₂₋₁₄ alkylammonium-N-oleoyl sarcosinate. 7.In an aerosol propellant for use in a water-based aerosol composition,the improvement which comprises the presence of a corrosion inhibitingcomposition comprising 15 to 85 wt. % of a nitroalkane containing 1-3carbon atoms and 85 to 15 wt. % of a tertiary C₁₂₋₁₄ alkylammoniumcarboxylate, said corrosion inhibiting composition being present in anamount sufficient to prevent more than light corrosion of a tin-platedsteel aerosol can containing said aerosol composition.
 8. Thecomposition of claim 7 in which the nitroalkane is nitromethane and thetertiary C₁₂₋₁₄ alkylammonium carboxylate is a tertiary C₁₂₋₁₄alkylammonium benzoate.
 9. The composition of claim 7 in which thenitroalkane is nitromethane and the tertiary C₁₂₋₁₄ alkylammoniumcarboxylate is a tertiary C₁₂₋₁₄ alkylammonium-N-oleoyl sarcosinate. 10.The composition of claim 7 comprising 15 to 50 wt % of a nitroalkanecontaining 1-3 carbon atoms and 85 to 50 wt % of a tertiary C₁₂₋₁₄alkylammonium carboxylate.
 11. The composition of claim 10 in which thenitroalkane is nitromethane and the tertiary C₁₂₋₁₄ alkylammoniumcarboxylate is a tertiary C₁₂₋₁₄ alkylammonium benzoate.
 12. Thecomposition of claim 10 in which the nitroalkane is nitromethane and thetertiary C₁₂₋₁₄ alkylammonium carboxylate is a tertiary C₁₂₋₁₄alkylammonium-N-oleoyl sarcosinate.